What makes up the
BIOSPHERE?
Energy and water exist and move around the biosphere in different forms/states
Where does energy come from?
Ecology can be studied at very large scales: Biosphere
“A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise” -Aldo Leopold
Painting Chalon Sombrero
Albedo
Global albedo is highly variable
Albedo feedbacks and Snowball Earth
Earth’s average albedo is ~0.3, keeping surface @ 15°C
Do you think global albedo is stable?
Albedo: cold generates cold but…..
Sun is the Earth’s primary form of heat energy, via radiation
- ~1/3 of sunlight energy reflects back to space
- Rest is absorbed by land, ocean and atmosphere
- Exact amount absorbed depends on both surface and atmosphere
- major contributor of the Earth Energy Budget
- The balance of incoming and outgoing radiation makes up the Earth Energy Budget
Why clouds are cool…
Greenhouse gas absorption spectra for outgoing radiation
Composition of the atmosphere alters the greenhouse effect
- Gases have different RESIDENCE TIMES
- N2 = 13 million years (inert)
- O2 = 10,000 years (inert)
- N20 = 114 years
- CH4 (methane) = 12 years
- CO2 = 5-200 years (1/2 removed quickly)
- Water vapor is reactive and highly variable
- 10 day residence time
- seasonally and spatially
Changes in composition impact atmospheric heating
Water vapor is the most abundant greenhouse gas
- NASA recently confirmed heat-trapping effect of water in the air
- critical component of climate change
- collects at tropical latitudes
- 2x climate warming caused by increased CO2
Solar energy & water cycle connected
Water cycle = movement of water within the earth and atmosphere
25% of incoming solar energy leaves the surface through evaporation
Evapotranspiration: Energetics of water movement
Water enters the atmosphere as vapor from surfaces (evaporation) and from leaves (transpiration)
- Water has high specific heat
- 4x more energy to heat water than air
- absorbs/holds solar energy well
- 30% of oceans evaporate per year
- >60% of rainfall is lost to evapotranspiration
- Large energy fluxes when water changes state
- evapotranspiration cools surfaces
- condensation warms atmosphere
Global water cycle: 577,000 km3 of water circulates each year
Global net movement as precipitation ≠evapotranspiration
Global water cycle: Residence times matter
Fresh water for humans….
